Injection needle assembly and medicine injection apparatus

ABSTRACT

An injection needle assembly includes: a needle tube; a needle hub holding the needle tube; a protector movable between a first position at which a needle tip of the needle tube is covered and a second position at which the needle tip of the needle tube is exposed; a biasing member configured to bias the protector toward the needle tip of the needle tube along an axial direction; a retaining member that supports the protector such that the protector is movable along the axial direction, wherein an abutment piece of the protector abuts on the retaining member when the protector is moved to the first position; and a restriction mechanism configured such that, after the protector has moved from the first position to the second position and back to the first position, the restriction mechanism restricts the protector from moving from the first position to the second position again.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application in a bypass continuation of PCT Application No.PCT/JP2016/055997, filed on Feb. 29, 2016, which claims priority toJapanese Application No. 2015-065473, filed on Mar. 27, 2015. Thecontents of these applications are hereby incorporated by reference intheir entireties.

BACKGROUND

The present application relates to an injection needle assembly and amedicine injection apparatus which are used to puncture a surface ofskin with a needle tip and inject a medicine into a skin upper layerportion.

BACKGROUND ART

In recent years, human infection with avian influenza has been reported,and there are growing concerns about damage due to an outbreak(pandemic) of infection from individual to individual. For this reason,pre-pandemic vaccines which can be effective for avian influenza havebeen stockpiled all over the world. In addition, in order to administerpre-pandemic vaccines to many humans, a study for increasing theproduction volume of the vaccines has been conducted.

The skin includes three portions: the epidermis, the dermis, and thesubcutaneous tissue. The epidermis is a layer of about 50 to 200 μm froma skin surface, and the dermis is a layer of about 1.5 to 3.5 mmcontinuing from the epidermis. Because influenza vaccine is generallyadministered subcutaneously or intramuscularly, the vaccine isadministered to a lower layer of the skin or a part deeper than thelower layer.

It has been reported that even when a dosage amount is reduced byadministration of the influenza vaccine to a target region which is askin upper layer portion where many immunocytes are present, an immunityacquiring ability equivalent to that of hypodermic or intramuscularadministration is obtained. Thus, because the dosage amount can bereduced by administration of the pre-pandemic vaccine to the skin upperlayer portion (i.e., the epidermis and the dermis of the skin), thepre-pandemic vaccine can be administered to more individuals.

Various methods using a single needle, multiple needles, a patch, gas,etc. have been reported as methods for administering a medicine to theskin upper layer portion. Considering administration stability,reliability, and a manufacturing cost, the method using the singleneedle is most suitable as the method for administration to the skinupper layer portion. A Mantoux's test is known as a method foradministering a vaccine to the skin upper layer portion by means of thesingle needle. The Mantoux's test is generally a method foradministering a medicine of about 100 μl in such a manner that a needlehaving a short bevel needle tip with a size of 26 to 27 gauge is, from adiagonal direction of about 10 to 15°, inserted into the skin by about 2to 5 mm.

However, it is difficult to perform the technique of the Mantoux's testfor medicine administration, and for this reason, the success rate ofthe Mantoux's test depends on the skill of a doctor who performs theinjection. There is a probability that an individual, especially achild, moves during administration, and for this reason, it is difficultto administer the influenza vaccine by the Mantoux's test. Thus, thereis a demand for development of a device configured to easily administera vaccine to the skin upper layer portion.

JP 2001-137343 A describes an injection apparatus for a skin upper layerportion in which a limiter having a skin contact surface is connected toa needle hub. The limiter described in JP 2001-137343 A is providedaround a needle tube and has a gap against the needle tube. A medicineis administered into the skin by restricting a length (protrusionlength) of the needle tube protruding from a surface of the limitercontacting the skin to 0.5 to 3.0 mm.

SUMMARY

In the injection apparatus described in JP 2001-137343 A, however, aneedle distal end portion of the needle tube always protrudes from thesurface of the limiter contacting the skin, and thus, there is apossibility that a needle tip of the needle tube may erroneouslypuncture a user after administration of the medicine or at the time ofdisposal of the medicine injection apparatus, which is problematic.

An object of certain embodiments of the present invention is to providean injection needle assembly and a medicine injection apparatus capableof inhibiting a needle tip of a needle tube from erroneously puncturinga user after administration of a medicine or at the time of disposal.

In one embodiment, an injection needle assembly includes: a needle tubehaving a needle tip capable of puncturing a living body; a needle hubwhich holds the needle tube; a protector; a biasing member; a retainingmember; and a restriction mechanism. The protector is movable to a firstposition to cover the needle tip of the needle tube and a secondposition to expose the needle tip of the needle tube. The biasing memberbiases the protector toward the needle tip side of the needle tube alongan axial direction of the needle tube. The retaining member supports theprotector so as to be movable along the axial direction of the needletube, and an abutment piece provided on the protector abuts on theretaining member when the protector is moved to the first position. Therestriction mechanism restricts the protector from moving again from thefirst position to the second position after the protector moves from thefirst position to the second position and further moves from the secondposition to the first position.

In another embodiment, a medicine injection apparatus includes: theabove-described injection needle assembly; and a syringe that isdetachably attached to the injection needle assembly.

According to certain embodiments of the injection needle assembly andthe medicine injection apparatus, it is possible to inhibit the needletip of the needle tube after use from puncturing against an intention ofthe user.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a medicine injection apparatusaccording to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating the medicine injectionapparatus according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view illustrating a state during puncture ofthe medicine injection apparatus according to the first embodiment ofthe present invention.

FIG. 4 is a cross-sectional view illustrating a state after puncture ofthe medicine injection apparatus according to the first embodiment ofthe present invention.

FIG. 5 is a cross-sectional view illustrating a medicine injectionapparatus according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a state during puncture ofthe medicine injection apparatus according to the second embodiment ofthe present invention.

FIG. 7 is a cross-sectional view illustrating a state after puncture ofthe medicine injection apparatus according to the second embodiment ofthe present invention.

DETAILED DESCRIPTION

Hereinafter, embodiments of an injection needle assembly and a medicineinjection apparatus will be described with reference to FIGS. 1 to 7.Common members are denoted by identical reference signs throughout thedrawings. the present invention is not limited to the followingembodiments.

The description will be given in the following order.

1. First Embodiment

1-1. Configuration Examples of Injection Needle Assembly and MedicineInjection apparatus

1-2. How to Use Medicine Injection apparatus

2. Second Embodiment

1. First Embodiment

1-1. Configuration Examples of Injection Needle Assembly and MedicineInjection Apparatus

First, an injection needle assembly and a medicine injection apparatusaccording to a first embodiment (hereinafter, referred to as the“present embodiment”) of the present invention will be described withreference to FIGS. 1 and 2.

FIG. 1 is a perspective view illustrating the medicine injectionapparatus of the present embodiment, and FIG. 2 is a sectional viewillustrating the injection needle assembly of the present embodiment.

A medicine injection apparatus 1 is used in the case of puncturing asurface of skin with a needle tip and injecting a medicine into a skinupper layer portion. As illustrated in FIG. 1, the medicine injectionapparatus 1 includes an injection needle assembly 2, a syringe 3 that isdetachably attached to the injection needle assembly 2, a pusher member4, and a syringe holder 5 that holds the syringe 3.

[Syringe]

The syringe 3 is a pre-filled syringe that is filled with a medicine inadvance. The syringe 3 has a syringe main body 11, a discharge partformed at first end portion in an axial direction of the syringe mainbody 11, a lock mechanism 12 provided in the discharge part, and agasket 13.

The syringe main body 11 is formed in a substantially cylindrical shapewith a hollow. In addition, the gasket 13 is disposed slidably in acylindrical hole of the syringe main body 11. The gasket 13 is formed ina substantially columnar shape and is in liquid-tight close contact withan inner peripheral surface of the cylindrical hole of the syringe mainbody 11. Further, the gasket 13 partitions an internal space of thesyringe main body 11 into two. A space closer to the discharge part sidethan the gasket 13 in the syringe main body 11 serves as a liquidchamber 14 that is filled with the medicine. On the other hand, aplunger main body 16 of the pusher member 4, which will be describedlater, is inserted into a space closer to the second end side than thegasket 13 in the syringe main body 11.

A material of the gasket 13 is not particularly limited, but it ispreferable to use an elastic material in order to obtain favorableliquid tightness with the syringe main body 11. Examples of the elasticmaterial may include various rubber materials, such as natural rubber,isobutylene rubber, and silicone rubber, various thermoplasticelastomers, such as an olefin type and a styrene type, or mixturesthereof.

An outer diameter and an inner diameter of the syringe main body 11 areappropriately set according to the use of the medicine injectionapparatus 1 and the volume of the medicine to be contained in the liquidchamber 14. For example, when the volume of the medicine to be containedis set to 0.5 mL using a general-purpose high-speed filling machine, itis preferable to set the inner diameter of the syringe main body 11 to4.4 to 5.0 mm and the outer diameter of the syringe main body 11 to 6.5to 8.4 mm. In addition, when the volume is set to 1 mL, it is preferableto set the inner diameter of the syringe main body 11 to 6.1 to 9.0 mmand the outer diameter of the syringe main body 11 to 7.9 to 12.5 mm.

Examples of the medicine may include various vaccines to inhibit variousinfectious diseases, such as influenza, but the medicine is not limitedto the vaccine. Examples of medicines other than the vaccine may includea sugar injection solution like glucose, an injection solution forcorrection of electrolyte, such as sodium chloride or potassium lactate,vitamins, antibiotic infusion solutions, contrast media, steroids,protease inhibitors, fat emulsions, anticancer agents, anesthetic,heparin calcium, antibody preparations, and the like.

A flange part 15 is formed at the second end portion in the axialdirection of the syringe main body 11. The flange part 15 is engagedwith an engaging part 5 a provided in the syringe holder 5 to bedescribed later. In addition, the discharge part (not illustrated) iscontinuously formed at first end portion in the axial direction of thesyringe main body 11.

The discharge part is formed in a substantially cylindrical shape to becoaxial with the syringe main body 11. In addition, a cylindrical holeof the discharge part communicates with the cylindrical hole of thesyringe main body 11. The discharge part is formed in a tapered shapewhose diameter continuously decreases toward the first end portion inthe axial direction. When the injection needle assembly 2 is attached tothe syringe 3, a distal end portion of the discharge part is inliquid-tight close contact with an end face of an elastic member 25 ofthe injection needle assembly 2 to be described later.

The lock mechanism 12 is provided in the discharge part. The lockmechanism 12 is a luer lock part representing an example of a fixingmechanism. The lock mechanism 12 is formed in a tubular shape thatcoaxially surrounds the discharge part. In addition, the lock mechanism12 has a circular inner periphery, and an outer periphery thereof isformed in a hexagonal shape. A female screw part is formed on an innerperipheral surface of the lock mechanism 12. The female screw part isformed so as to be screwable with a male screw part 52 b provided in theinjection needle assembly 2.

Examples of a material of the syringe main body 11 may include varioustypes of resin such as polyvinyl chloride, polyethylene, polypropylene,cyclic polyolefin, polystyrene, poly-(4-methylpentene-1), polycarbonate,acrylic resin, an acrylonitrile-butadiene-styrene copolymer, polyestersuch as polyethylene terephthalate, a butadiene-styrene copolymer, andpolyamide (for example, nylon 6, nylon 6/6, nylon 6/10, and nylon 12).Among them, it is preferable to use resin such as polypropylene, cyclicpolyolefin, polyester, and poly-(4-methylpentene-1) from the viewpointthat molding is easy. Incidentally, it is preferable that the materialof the syringe main body 11 be substantially transparent in order tosecure the visibility of the interior.

Although the example in which the pre-filled syringe, filled with themedicine in advance, is applied as the syringe 3 has been described inthe present embodiment, the present invention is not limited thereto,and a syringe in which the inside of a syringe main body is not filledwith a medicine in advance may be applied.

[Pusher Member]

The pusher member 4 has the plunger main body 16 and an operation part17 to operate the plunger main body 16. The plunger main body 16 isformed in a rod shape. The plunger main body 16 is inserted into thecylindrical hole of the syringe main body 11 from an opening portionformed at the second end portion in the axial direction of the syringemain body 11. Further, first end portion in an axial direction of theplunger main body 16 abuts on the gasket 13.

The operation part 17 is formed at the second end portion in the axialdirection of the plunger main body 16. The operation part 17 is formedin a substantially disc shape. When using the medicine injectionapparatus 1, the operation part 17 is pressed by a user. As a result,the first end portion in the axial direction of the plunger main body 16abuts on the gasket 13 to cause the gasket 13 to slide toward thedischarge part.

In addition, various types of resin exemplified as the material of thesyringe main body 11 can be applied as a material of the pusher member4.

[Syringe Holder]

Next, the syringe holder 5 will be described.

The syringe holder 5 is formed in a substantially cylindrical shape. Thesyringe holder 5 covers an outer peripheral surface of the syringe mainbody 11 and an outer peripheral surface of the lock mechanism 12 in thesyringe 3. The syringe holder 5 is configured to enable grip of the userat the time of attaching the injection needle assembly 2 to the syringe3.

A viewing window 18 is formed at first end portion in an axial directionof the syringe holder 5. The viewing window 18 is provided at a positionwhere the liquid chamber 14 of the syringe 3 is visible from the outsideof the syringe holder 5 when the syringe 3 is attached to the syringeholder 5. Accordingly, it is possible to secure the visibility of theinterior even if the syringe holder 5 is attached to the syringe 3.

In addition, the holder flange 19 is formed at the second end in theaxial direction of the syringe holder 5. The holder flange 19 protrudesto be substantially perpendicular to apart of the outer peripheralsurface of the syringe holder 5. Since the holder flange 19 is provided,it is possible to inhibit a finger gripping the syringe holder 5 fromslipping toward the second end portion in the axial direction when theuser grips the syringe holder 5 and administers the medicine. Inaddition, it is possible to inhibit the medicine injection apparatus 1from rolling when placing the medicine injection apparatus 1 on a desk,a table, or the like.

Further, the engaging part 5 a is provided in a middle portion in theaxial direction of the syringe holder 5. The engaging part 5 a is anopening portion that passes through an outer wall of the syringe holder5. The flange part 15 of the syringe 3 is engaged with the engaging part5 a.

It is possible to increase a diameter of the medicine injectionapparatus 1 by attaching the syringe holder 5 to the syringe 3 so thatit is easy to grip the medicine injection apparatus 1. As a result, theoperability at the time of operating the pusher member 4 is improved.

[Injection Needle Assembly]

Next, the injection needle assembly 2 will be described.

As illustrated in FIGS. 1 and 2, the injection needle assembly 2includes a hollow needle tube 21 and a needle hub 22 which holds theneedle tube 21.

[Needle Tube]

As illustrated in FIG. 2, a needle tube having a size (0.2 to 0.45 mm inoutside diameter) conforming to 26- to 33-gauge according to ISO medicalneedle tube standard (ISO9626:1991/Amd. 1:2001(E)) is used as the needletube 21, and preferably, a needle tube having a size of 30- to 33-gaugeis used. Incidentally, a needle smaller than 33-gauge may be used.

A needle tip 21 a having a blade surface is provided at a first end ofthe needle tube 21. Hereinafter, the second end of the needle tube 21 onthe opposite side to the needle tip 21 a will be referred to as a“proximal end”. A length in the axial direction of the needle tube 21 onthe blade surface (hereinafter, referred to as a “bevel length”) ispreferably 1.4 mm (adults) or less, which is a minimum thickness of theskin upper layer portion to be described later, and is preferably about0.5 mm or more which is a bevel length in the case where a short bevelis formed in the needle tube of 33-gauge. That is, the bevel length ispreferably set in a range of 0.5 to 1.4 mm.

Further, the bevel length is more preferable if the minimum thickness ofthe skin upper layer portion is 0.9 mm (children) or less, that is, thebevel length is in a range of 0.5 to 0.9 mm. Incidentally, the shortbevel indicates a blade surface formed at an angle of 18 to 25° relativeto a longitudinal direction of the needle that is commonly used for aninjection needle.

For example, stainless steel can be exemplified as a material of theneedle tube 21, but the material is not limited thereto, and it ispossible to use aluminum, an aluminum alloy, titanium, a titanium alloy,and other metals. In addition, not only a straight needle but also atapered needle having at least a part formed in a tapered shape can beused as the needle tube 21. The tapered needle may be obtained byforming a proximal end portion to have a larger diameter than a distalend portion of the needle and an intermediate portion thereof to have atapered structure. In addition, a sectional shape of the needle tube 21may be not only a circular shape but also a polygonal shape such as atriangle.

[Needle Hub]

The needle hub 22 includes a first member 23 which holds the needle tube21, a second member 24 into which the discharge part of the syringe 3 isfitted, the elastic member 25, a protector 26, a biasing member 27, arestriction mechanism 28. The first member 23 and the second member 24are formed as separate members. Examples of materials of the firstmember 23 and the second member 24 may include synthetic resin such aspolycarbonate, polypropylene, and polyethylene.

The first member 23 includes a base part 31, an adjustment part 32, astabilization part 33, a guide part 34, and a support part 37. The basepart 31 is formed in a substantially columnar shape. A housing recess 36is formed in the base part 31. The housing recess 36 is formed to berecessed in a substantially columnar shape from a first end to a secondend in an axial direction of the base part 31. Further, the entire firstend face in the axial direction of the base part 31 is opened. Thesupport part 37 is provided in the housing recess 36.

The support part 37 is provided at a central portion of a bottom surface36 a of the housing recess 36 and protrudes from the bottom surface 36 aof the housing recess 36 toward the one side in the axial direction ofthe base part 31. The support part 37 is formed in a substantiallycolumnar shape.

In addition, the adjustment part 32 is continuously provided on a firstend face in an axial direction of the support part 37. The adjustmentpart 32 is a columnar protruding part that protrudes in the axialdirection of the support part 37. An axial center of the adjustment part32 coincides with each axis of the base part 31 and the support part 37.

A through hole 39 through which the needle tube 21 passes is provided inthe axial centers of the base part 31, the support part 37, and theadjustment part 32. The base part 31 is provided with an injection hole44 configured to inject an adhesive material into the through hole 39.The injection hole 44 is opened to the outer peripheral surface of thebase part 31 closer to the other side in the axial direction than thehousing recess 36, and communicates with the through hole 39. That is,the needle tube 21 is fixed to the base part 31 and the support part bythe adhesive material injected from the injection hole 44 into thethrough hole 39.

The proximal end side of the needle tube 21 protrudes from an end face31 a of the base part 31 on the other side in the axial direction. Thebase part 31 is inserted into the second member 24 from the end face 31a, and the proximal end side of the needle tube 21 is inserted into aninsertion hole of the elastic member 25. Further, the end face 31 a ofthe base part 31 abuts on an end face of the elastic member 25.

In addition, a connection piece 35 is provided on the outer peripheralsurface of the base part 31. The connection piece 35 is formed as aring-shaped flange part that protrudes outward in a radial direction ofthe base part 31 on a first end side in the axial direction of the basepart 31. The connection piece 35 has flat surfaces 35 a and 35 bopposing each other in the axial direction of the base part 31. Thesecond member 24 is connected to the flat surface 35 b of the connectionpiece 35. In addition, a distal end portion of the connection piece 35forms the guide part 34. The guide part 34 will be described later indetail.

The end face of the adjustment part 32 forms a needle protrusion surface32 a on which the needle tip 21 a side of the needle tube 21 protrudes.The needle protrusion surface 32 a is formed as a flat surfaceorthogonal to the axial direction of the needle tube 21. This needleprotrusion surface 32 a defines a depth of puncture of the needle tube21 in contact with the surface of the skin when puncturing the skinupper layer portion with the needle tube 21. That is, the depth ofpuncture of the needle tube 21 in the skin upper layer portion isdetermined by a length (hereinafter, referred to as a “protrusion lengthL”) of the needle tube 21 protruding from the needle protrusion surface32 a (see FIG. 3).

A thickness of the skin upper layer portion corresponds to a depth fromthe surface of the skin to a dermis layer and is generally in a range of0.5 to 3.0 mm. Thus, the protrusion length L of the needle tube 21 canbe set within the range of 0.5 to 3.0 mm.

Meanwhile, an administration site of an influenza vaccine is generallythe deltoid muscle. In view of this, the thickness of the skin upperlayer portion at the deltoid muscle was measured for 19 infants and 31adults. The measurement was conducted by imaging the skin upper layerportion where ultrasonic reflectance is high using an ultrasonicmeasuring instrument (NP60R-UBM, a high-resolution echo system for smallanimals, manufactured by NEPA GENE CO., LTD.). Incidentally, measurementvalues were in log-normal distribution so that a range of MEAN±2SD wasobtained by a geometric mean.

As a result, the thickness of the skin upper layer portion at thedeltoid muscle of children was 0.9 to 1.6 mm. In addition, the thicknessof the skin upper layer portion at the deltoid muscle of adults was 1.4to 2.6 mm in a distal region, 1.4 to 2.5 mm in a central region, and 1.5to 2.5 mm in a proximal region. From the above, it was confirmed thatthe thickness of the skin upper layer portion at the deltoid muscle is0.9 mm or more in the case of children, and 1.4 mm or more in the caseof adults. Therefore, it is preferable to set the protrusion length L ofthe needle tube 21 in a range of 0.9 to 1.4 mm at the time of injectioninto the skin upper layer portion at the deltoid muscle.

When the protrusion length L is set as described above, it is possibleto position the blade surface of the needle tip 21 a in the skin upperlayer portion. As a result, a needle hole (medicine discharge port)opening to the blade surface is positioned in the skin upper layerportion at any position in the blade surface. Even if the medicinedischarge port is positioned in the skin upper layer portion, themedicine flows into a subcutaneous tissue from a portion between a sidesurface of the end portion of the needle tip 21 a and the incised skinwhen the needle tip 21 a is stuck to be deeper than the skin upper layerportion, and thus, it is important that the blade surface is reliablypresent in the skin upper layer portion.

It is difficult to set the bevel length to be 1.0 mm or less with aneedle tube larger than 26-gauge in the case of being used foradministration to the skin upper layer portion. Therefore, it ispreferable to use a needle tube narrower than 26-gauge in order to setthe protrusion length L of the needle tube 21 to the preferable range(0.9 to 1.4 mm).

The needle protrusion surface 32 a of the adjustment part 32 is formedsuch that a distance S from a peripheral edge to the outer peripheralsurface of the needle tube 21 is 1.4 mm or less, and is preferablyformed in a range of 0.3 to 1.4 mm. The distance S from the peripheraledge of the needle protrusion surface 32 a to the peripheral surface ofthe needle tube 21 is set upon considering that pressure is applied to ablister formed by administering the medicine to the skin upper layerportion. That is, the needle protrusion surface 32 a is set to a sizethat is sufficiently smaller than the blister formed in the skin upperlayer portion and does not to hinder the formation of the blister. As aresult, it is possible to inhibit the administered medicine from leakingeven if the needle protrusion surface 32 a presses the skin around theneedle tube 21.

The stabilization part 33 is formed in a tubular shape protruding fromthe flat surface 35 a of the connection piece 35. The needle tube 21,the adjustment part 32, and the protector 26, which will be describedlater, are disposed in a cylindrical hole of the stabilization part 33.That is, the stabilization part 33 is formed in the tubular shape tocover the adjustment part 32 through which the needle tube 21 passes andthe periphery of the protector 26, and is provided to be spaced partfrom the needle tip 21 a of the needle tube 21 in the radial direction.

An end face 33 a of the stabilization part 33 is positioned closer tothe proximal end side of the needle tube 21 than the needle protrusionsurface 32 a of the adjustment part 32. When the living body ispunctured with the needle tip 21 a of the needle tube 21, the needleprotrusion surface 32 a first comes into contact with the surface of theskin, and then, the end face 33 a of the stabilization part 33 comesinto contact with the surface of the skin. At this time, the medicineinjection apparatus 1 is stabilized as the end face 33 a of thestabilization part 33 comes into contact with the skin, and it ispossible to maintain the needle tube 21 in a posture that issubstantially perpendicular to the skin.

Incidentally, it is possible to maintain the needle tube 21 in theposture that is substantially perpendicular to the skin even if the endface 33 a of the stabilization part 33 is positioned on the same planeas the needle protrusion surface 32 a or positioned to be closer to theneedle tip 21 a side of the needle tube 21 than the needle protrusionsurface 32 a. When considering the swell of the skin when thestabilization part 33 is pushed to the skin, a distance in the axialdistance between the end face 33 a of the stabilization part 33 and theneedle protrusion surface 32 a is preferably set to 1.3 mm or less.

In addition, an inner diameter d of the stabilization part 33 is set toa value which is equal to or larger than a diameter of the blisterformed on the skin. Specifically, a distance T from an inner wallsurface of the stabilization part 33 to the peripheral edge of theneedle protrusion surface 32 a is set to be in a range of 4 mm to 15 mm.Accordingly, no pressure is applied to the blister from the inner wallsurface of the stabilization part 33, and it is possible to inhibit theblister formation from being hindered.

The distance T from the inner wall surface of the stabilization part 33to the needle protrusion surface 32 a is not particularly limited aslong as being 4 mm or more. However, an outer diameter of thestabilization part 33 increases when the distance T increases, and it isdifficult to bring the entire end face 33 a of the stabilization part 33into contact with the skin in the case of puncturing a narrow arm of achild with the needle tube 21. Thus, it is preferable that the maximumof the distance T be defined as 15 mm in consideration of the narrownessof the arm of the child.

If the distance S from the needle protrusion surface 32 a to the outerperipheral surface of the needle tube 21 is 0.3 mm or more, theadjustment part 32 does not enter the skin. Therefore, it is possible toset the inner diameter d of the stabilization part 33 to 9 mm or morewhen considering the distance T (4 mm or more) from the inner wallsurface of the stabilization part 33 to the peripheral edge of theneedle protrusion surface 32 a and the diameter (about 0.3 mm) of theneedle protrusion surface 32 a.

Incidentally, the shape of the stabilization part 33 is not limited tothe cylindrical shape, and may be formed in a square tubular shape, suchas a quadrangular prism and a hexagonal prism, having a cylindrical holein the center, for example.

The guide part 34 is a portion on the distal end side that is positionedoutward in the radial direction of the first member 23 of thestabilization part 33 in the connection piece 35. The guide part 34 hasa contact surface 34 a which comes into contact with the skin. Thecontact surface 34 a is a part of the flat surface 35 a of theconnection piece 35 and is a flat surface that is substantially parallelto the end face 33 a of the stabilization part 33. It is possible toconstantly secure the force pressing the skin of the stabilization part33 and the needle tube 21 at a predetermined value or more by pushingthe stabilization part 33 until the contact surface 34 a of the guidepart 34 comes into contact with the skin. Accordingly, a portion(corresponding to the protrusion length L) of the needle tube 21 thatprotrudes from the needle protrusion surface 32 a is reliably stuck intothe skin.

A length of a distance (hereinafter, referred to as “guide part height”)Y from the contact surface 34 a of the guide part 34 to the end face 33a of the stabilization part 33 is set such that the needle tube 21 andthe stabilization part 33 can press and puncture the skin with anappropriate pressing force. Incidentally, the appropriate pressing forceof the needle tube 21 and the stabilization part 33 is, for example, 3to 20 N. Accordingly, the guide part 34 guides the pressing force,generated by the needle tube 21 and the stabilization part 33, to theskin, and it is possible to reliably position the needle tip 21 a of theneedle tube 21 in the skin upper layer portion and to grant the user asense of security.

The guide part height Y is appropriately determined based on the innerdiameter d of the stabilization part 33 and a length (hereinafter,referred to as a “guide part length”) X from a distal end face of theguide part 34 to the outer peripheral surface of the stabilization part33. For example, when the inner diameter d of the stabilization part 33is 12 mm and the guide part length X is 3.0 mm, the guide part height Yis set in a range of 2.3 to 6.6 mm.

Next, the protector 26 will be described. As illustrated in FIG. 1 andFIG. 2, the protector 26 covers the adjustment part 32 through which theneedle tube 21 passes and the periphery of the needle tip 21 a of theneedle tube 21 in the state before puncturing the skin with the needletube 21.

In addition, the protector 26 is formed in a cylindrical shape. Theprotector 26 is supported by the support part 37 and the retainingmember 43 so as to be movable in axial directions thereof (the axialdirection of the needle tube 21). Further, a part of the other side inthe axial direction of the protector 26 is inserted into a space 40 thatis formed between the housing recess 36 and the support part 37.

It is preferable to set a wall thickness of the protector 26 to besufficiently smaller than the diameter of the needle protrusion surface32 a in order to inhibit the formation of the blister from beinghindered.

An abutment piece 29 is provided on a side of the protector 26 oppositeto the needle tip 21 a of the needle tube 21, that is, the second endside in the axial direction. The abutment piece 29 is formed as aring-shaped flange part protruding outward in the radial direction froman outer peripheral surface of the protector 26. In addition, aninclined surface 29 a is provided at an outer edge on the outer side inthe radial direction of the abutment piece 29. The inclined surface 29 ais provided at a corner portion of the outer edge of the abutment piece29 on the needle tip 21 a side of the needle tube 21. The inclinedsurface 29 a is formed into a tapered shape whose diameter continuouslydecreases from the other side to the one side in the axial direction.

In addition, an engagement member 41 and an extension member 42 of therestriction mechanism 28, which will be described later, are disposed onthe other side in the axial direction of the protector 26.

The shape of the protector 26 is not limited to the cylindrical shape,but may be formed into a square tubular shape, such as a quadrangularprism and a hexagonal prism, having a cylindrical hole in the center,for example.

The biasing member 27 is disposed in the space 40 formed in the housingrecess 36 and is interposed between the second end face in the axialdirection of the protector 26 and the bottom surface 36 a of the housingrecess 36. Further, the biasing member 27 is disposed so as to cover theperiphery of the outer peripheral surface of the support part 37.

The biasing member 27 is a compression coil spring and biases theprotector 26 toward the one side in the axial direction, that is, theneedle tip 21 a side of the needle tube 21. A biasing force of thebiasing member 27 is set to be smaller than the appropriate pressingforce at the time of puncturing the skin with the needle tube 21, and isset to, for example, 3 N or less. Accordingly, the biasing force of thebiasing member 27 does not hinder the positioning of the needle tip 21 aof the needle tube 21 in the skin upper layer portion at the time ofpuncturing the skin with the needle tube 21, and thus, it is possible toreliably position the needle tip 21 a of the needle tube 21 in the skinupper layer portion.

Although the example in which the compression coil spring is applied asthe biasing member 27 has been described in the present embodiment, thepresent invention is not limited thereto. The biasing member may be anyelastic member that elastically deforms when a predetermined pressingforce is applied, and it is possible to apply, for example, othervarious spring members such as a leaf spring, a sponge, a gel, and arubber member.

Next, the restriction mechanism 28 will be described. The restrictionmechanism 28 has the engagement member 41 and the extension member 42.The engagement member 41 has a cylindrical part 45 formed in asubstantially cylindrical shape and a plurality of engaging parts 46.

The engagement member 41 is disposed in the housing recess 36. Further,the cylindrical part 45 is fixed to the bottom surface 36 a of thehousing recess 36. Further, the engagement member 41 is disposed so asto cover the periphery of the other side of the support part 37 in theaxial direction. The plurality of engaging parts 46 are continuouslyformed on one side in an axial direction of the cylindrical part 45.

The plurality of engaging parts 46 are provided on a first end face inthe axial direction of the cylindrical part 45 at a predeterminedinterval along a circumferential direction thereof. The plurality ofengaging parts 46 protrude in a substantially flat plate shape from thefirst end face in the axial direction of the cylindrical part 45. Inaddition, the plurality of engaging parts 46 are formed in a tongueshape and are provided with elasticity.

A distal end portion of the engaging part 46 is inclined with respect tothe axial direction of the needle tube 21 so as to approach the innerside in the radial direction than a proximal end portion on thecylindrical part 45 side, that is, the support part 37. An engagementpiece 46 a is provided on a surface on the inner side in the radialdirection of the distal end portion of the plurality of engaging parts46. The engagement piece 46 a protrudes to be substantiallyperpendicular to the inner side in the radial direction from the surfaceon the inner side of the engaging part 46.

In addition, a diameter of a space, formed by the plurality of engagingparts 46 when the plurality of engaging parts 46 are in a natural statewithout being elastically deformed, is set to be slightly smaller thanan outer diameter of the abutment piece 29 of the protector 26. Further,the extension member 42 is disposed between the plurality of engagingparts 46 of the engagement member 41.

The extension member 42 is formed in a substantially cylindrical shape.The extension member 42 is detachably attached to an outer peripheralportion of the protector 26 on the other side in the axial directionwith respect to the abutment piece 29. An extension part 48 is providedon one side in an axial direction of the extension member 42.

The extension part 48 overhangs outward in the radial direction from anouter peripheral surface of the extension member 42. First end portionin an axial direction of the extension part 48 has an outer diametercontinuously increasing from the other side in the axial direction ofthe extension member 42 toward one side. An extension surface 48 a ofthe extension part 48 inclined with respect to the axial direction isheld by the plurality of engaging parts 46 of the engagement member 41.

In addition, a diameter of a portion where the outer diameter of theextension part 48 is the largest (hereinafter, referred to as a “maximumouter diameter”) is set to be larger than the diameter of the spaceformed by the plurality of engaging parts 46 when the plurality ofengaging parts 46 are in the natural state without being elasticallydeformed. Further, the maximum outer diameter of the extension part 48is set to be larger than the outer diameter of the abutment piece 29 ofthe protector 26. In addition, first end portion in the axial directionof the extension part 48 is engaged with the engagement pieces 46 aprovided in the plurality of engaging parts 46 of the engagement member41 in the extension member 42 after the puncture.

In addition, the first member 23 has the retaining member 43. Theretaining member 43 is formed in a substantially disc shape. Theretaining member 43 is fixed to the base part 31 so as to close anopening of the housing recess 36 on one side in the axial direction. Asupport hole 43 a is opened in a central portion of the retaining member43. The adjustment part 32, the support part 37, and the protector 26are inserted through the support hole 43 a. Further, the retainingmember 43 supports the protector 26 so as to be movable along the axialdirection of the support part 37.

In addition, the abutment piece 29 of the protector 26 abuts on thesecond end face in the axial direction of the retaining member 43 in thestate before puncturing the skin with the needle tube 21. Accordingly,it is possible to inhibit the protector 26 biased by the biasing member27 from falling out of the first member 23.

[Second Member]

Next, the second member 24 will be described. The second member 24 isformed in a tubular shape. First end portion in an axial direction ofthe second member 24 forms an insertion part 51 into which the base part31 of the first member 23 is inserted, and the second end portionthereof forms a fitting part 52 into which the discharge part of thesyringe 3 is fitted. A cylindrical hole 51 a of the insertion part 51 isset to a size corresponding to the base part 31 of the first member 23.

A fixing piece 54 is provided on an outer peripheral surface of firstend portion of the insertion part 51 in the axial direction of thesecond member 24. The fixing piece 54 is formed as a ring-shaped flangewhich is continuous to a distal end of the insertion part 51 andprotrudes outward in the radial direction. The flat surface 35 b of theconnection piece 35 provided in the first member 23 abuts on and isfixed to the fixing piece 54. For example, an adhesive, ultrasonicwelding, laser welding, a fixing screw, and the like can be used as amethod of fixing the fixing piece 54 and the connection piece 35.

An outer diameter of the fitting part 52 is set to be smaller than anouter diameter of the insertion part 51. Further, a cylindrical hole 52a of the fitting part 52 is set to a size corresponding to the dischargepart of the syringe 3 and has a diameter continuously decreasing towardthe insertion part 51 side. In addition, a male screw part 52 bconfigured to be screwed with the lock mechanism 12 of the syringe 3 isprovided on an outer peripheral surface of the fitting part 52 (see FIG.1). In addition, the elastic member 25 is disposed between thecylindrical hole 51 a of the insertion part 51 and the cylindrical hole52 a of the fitting part 52.

[Elastic Member]

Next, the elastic member 25 will be described. The elastic member 25 ismade of an elastically deformable member. Elastic materials, forexample, various rubber materials, such as natural rubber, siliconerubber, and isobutylene rubber, various thermoplastic elastomers, suchas a polyurethane type and a styrene type, or mixtures thereof can beused as a material of the elastic member 25.

The elastic member 25 is disposed inside the second member 24 andinterposed between the first member 23 and the syringe 3. Further, a gapgenerated between the outer peripheral surface on the proximal end sideof the needle tube 21 protruding from the first member 23 and the secondmember 24 is embedded by the elastic member 25. Further, the elasticmember 25 is elastically deformed to come into liquid-tight closecontact with the outer peripheral surface of the needle tube 21 when thedischarge part of the syringe 3 is fitted into the second member 24.Accordingly, it is possible to inhibit the medicine filled in thesyringe 3 from penetrating between the needle tube 21 and the elasticmember 25 and leaking out toward the first member 23 side.

1-2. How to Use Medicine Injection Apparatus

Next, how to use the medicine injection apparatus 1 having theabove-described configuration will be described with reference to FIGS.1 to 4.

FIG. 3 is a cross-sectional view illustrating a main part of themedicine injection apparatus 1 during puncture, and FIG. 4 is across-sectional view illustrating the main part of the medicineinjection apparatus 1 after puncture.

First, the syringe 3 is attached to the injection needle assembly 2 inadvance as illustrated in FIGS. 1 and 2. Specifically, the dischargepart of the syringe 3 is inserted into the fitting part 52 of the secondmember 24, and the lock mechanism 12 is screwed with the male screw part52 b. Accordingly, the attachment of the injection needle assembly 2 tothe syringe 3 is completed.

At this time, the abutment piece 29 abuts on the retaining member 43while the protector 26 is biased toward the first end side in the axialdirection by the biasing member 27. Accordingly, it is possible toinhibit the protector 26 from falling out of the support part 37 of thefirst member 23. A position of the protector 26 at this time is set as afirst position.

Further, the needle tip 21 a of the needle tube 21 is covered with theprotector 26 and is housed in the cylindrical hole of the protector 26.Accordingly, it is possible to inhibit the needle tip 21 a of the needletube 21 from puncturing against an intention of the user in the statebefore the puncture.

Next, the end face 33 a of the stabilization part 33 is caused to opposethe skin. Accordingly, the needle tip 21 a of the needle tube 21 iscaused to oppose the skin to be punctured. Next, the medicine injectionapparatus 1 is moved to be substantially perpendicular to the skin.Accordingly, a distal end face 26 a of the protector 26 is pushed to theskin. Further, when the medicine injection apparatus 1 is pushed to theskin against the biasing force of the biasing member 27, the protector26 moves in the axial direction of the support part 37, that is, alongthe axial direction of the needle tube 21. Accordingly, the needleprotrusion surface 32 a of the adjustment part 32 and the needle tip 21a side of the needle tube 21 protrude from a first end in the axialdirection of the protector 26, that is, from the distal end face 26 a,and the needle tip 21 a side of the needle tube 21 is exposed. Aposition of the protector 26 at this time is set as a second position.

An inner peripheral surface of the protector 26 is supported by theouter peripheral surface of the support part 37, and the outerperipheral surface thereof is supported by the support hole 43 a of theretaining member 43. Thus, the protector 26 can be smoothly movedwithout rattling.

When the protector 26 moves from one side to the other side in the axialdirection of the support part 37, the extension member 42 is pressed bythe abutment piece 29 of the protector 26 and moves together with theprotector 26 from the one side to the other side in the axial directionof the support part 37. When the extension member 42 moves from one sideto the other side in the axial direction of the support part 37, theplurality of engaging parts 46 that abut on the extension surface 48 aof the extension part 48 are pressed by the extension part 48.

First end portion in an axial direction of the extension part 48 has anouter diameter continuously increasing from the other side in the axialdirection of the extension member 42 toward one side. Thus, theplurality of engaging parts 46 are pressed outward in the radialdirection. Further, the plurality of engaging parts 46 are elasticallydeformed so as to pivot about the proximal end portion on thecylindrical part 45 side, and an opening surrounded by the plurality ofengaging parts 46 is pushed to spread outward in the radial direction.Accordingly, the abutment piece 29 of the protector 26 is inserted intothe engagement member 41 together with the extension member 42 withoutbeing caught by the plurality of engaging parts 46 as illustrated inFIG. 3.

In addition, when the extension part 48 of the extension member 42 andthe abutment piece 29 of the protector 26 pass over the engagement piece46 a of the plurality of engaging parts 46, the pressing force withrespect to the plurality of engaging parts 46 is released. Further, theplurality of engaging parts 46 are restored to the original shape(natural state) by their own elasticity. At this time, the biasingmember 27 is compressed by being elastically deformed between theabutment piece 29 of the protector 26 and the bottom surface 36 a of thehousing recess 36.

Further, the medicine injection apparatus 1 is moved to be substantiallyperpendicular to the skin, and the end face 33 a of the stabilizationpart 33 is pushed to the skin at the same time of puncturing the skinwith the needle tip 21 a. At this time, the needle protrusion surface 32a can contact the skin to cause the skin to be deformed to be flat, andthe needle tip 21 a side of the needle tube 21 can be stuck into theskin by the protrusion length L.

Next, the end face 33 a of the stabilization part 33 is pushed until thecontact surface 34 a of the guide part 34 comes into contact with theskin. Here, the length of the guide part height Y (see FIG. 2) is setsuch that the skin can be punctured by the needle tube 21 and thestabilization part 33 with the appropriate pressing force. Thus, a forcepressing the skin by the stabilization part 33 becomes a predeterminedvalue.

As a result, it is possible to cause the user to recognize theappropriate pressing force of the stabilization part 33, and to reliablyposition the needle tip 21 a and the blade surface of the needle tube 21in the skin upper layer portion. As the guide part 34 serves as a markfor recognition of the appropriate pressing force of the stabilizationpart 33 in this manner, the user can use the medicine injectionapparatus 1 at ease.

In addition, the posture of the medicine injection apparatus 1 isstabilized as the stabilization part 33 comes into contact with theskin, and the needle tube 21 can be stuck straight to the skin. Inaddition, it is possible to inhibit shaking occurring in the needle tube21 after puncture and to perform the stable administration of themedicine.

Further, there is a case where a needle tube having a very shortprotrusion length of, for example, about 0.5 mm is not stuck to the skineven by causing a needle tip to abut on the skin. However, the skin onthe inner side of the stabilization part 33 is pulled as the skin pushedagainst the stabilization part 33 is pushed down in the verticaldirection so that a state where a tensile force is applied to the skinis formed Thus, the skin hardly escapes with respect to the needle tip21 a of the needle tube 21. Therefore, it is also possible to obtain aneffect of causing the needle tip 21 a to be more easily stuck to theskin by providing the stabilization part 33.

In addition, when the above-described configuration is applied to ahypodermic injection apparatus which punctures a layer lower than a skinupper layer portion with a needle tube, a length of the needle tubepuncturing the skin is longer than that of the injection needle assembly2 which punctures the upper skin portion with the needle tube 21according to the present embodiment, and thus, a length in the axialdirection of the protector 26 increases. Thus, not only a length in theaxial direction of the support part 37 supporting the protector 26, butalso a movement distance of the protector 26 along the axial directionof the support part 37 becomes long. As a result, it is necessary toincrease a length in the axial direction of the housing recess 36provided in the base part 31 in the hypodermic injection apparatus, andthere is a problem that the first member and the injection needleassembly become large.

On the other hand, since the injection needle assembly 2 according tothe present embodiment is configured to puncture the skin upper layerportion with the needle tip 21 a of the needle tube 21, the protrusionlength L of the needle tube 21 is 0.5 to 3.0 mm, which is extremelyshort. Thus, it is possible to decrease the length in the axialdirection of the protector 26, and further, it is also possible tosignificantly decrease the movement distance of the protector 26 alongthe axial direction of the support part 37. As a result, it is possibleto inhibit the entire injection needle assembly 2 from becoming largeeven if the above-described configuration is applied to the injectionneedle assembly 2.

After puncturing the skin with the needle tip 21 a side of the needletube 21, the pusher member 4 (see FIG. 1) is pushed to move the gasket13 to the discharge part side. Accordingly, the medicine filled in theliquid chamber 14 of the syringe 3 is pushed out from the discharge partand is injected from the needle tip 21 a into the skin upper layerportion through the needle hole of the needle tube 21. At this time, itis possible to reduce the residual amount of the medicine since no spaceis formed between the distal end of the discharge part and the proximalend of the needle tube 21.

When the administration of the medicine is completed, the medicineinjection apparatus 1 is separated from the skin, and the end face 33 aof the stabilization part 33, the needle protrusion surface 32 a, andthe distal end face 26 a of the protector 26 are moved away from theskin. At this time, the biasing member 27 is released from pressing fromthe skin via the protector 26. Then, the protector 26 is biased towardthe needle tip 21 a side of the needle tube 21 by a restoring force(biasing force) of the biasing member 27. Thus, the protector 26 issupported by the outer peripheral surface of the support part 37 and thesupport hole 43 a of the retaining member 43 and moves toward one sidefrom the other side in the axial direction of the support part 37 asillustrated in FIG. 4.

When the protector 26 moves toward one side from the other side in theaxial direction of the support part 37, the inclined surface 29 a of theabutment piece 29 abuts on the engagement pieces 46 a of the pluralityof engaging parts 46. The inclined surface 29 a is formed into a taperedshape whose diameter continuously decreases from the other side to theone side in the axial direction. Thus, the plurality of engaging parts46 are pressed outward in the radial direction, and the space surroundedby the plurality of engaging parts 46 is pushed to spread outward in theradial direction. Accordingly, the abutment piece 29 can pass the spaceamong the plurality of engaging parts 46 without being caught by theplurality of engaging parts 46. In addition, when passing through theabutment piece 29, the pressing force with respect to the plurality ofengaging parts 46 is released, and the plurality of engaging parts 46are restored to the original shape (natural state) by their ownelasticity.

Further, the abutment piece 29 abuts against the retaining member 43 sothat the movement of the protector 26 in the axial direction isrestricted. In addition, it is possible to inhibit the protector 26 fromfalling out of the support part 37 of the first member 23.

The protector 26 covers the periphery of the needle tip 21 a of theneedle tube 21, and the needle tube 21 is housed in the protector 26.That is, the protector 26 returns from the second position to the firstposition. Accordingly, it is possible to automatically move theprotector 26 in accordance with the puncture operation and to easilycover the periphery of the needle tip 21 a of the needle tube 21.

On the other hand, the maximum outer diameter of the extension part 48is set to be larger than the outer diameter of the abutment piece 29 ofthe protector 26 in the extension member 42. Further, first end portionin the axial direction of the extension part 48 is engaged with theengagement pieces 46 a of the plurality of engaging parts 46. Thus, theextension member 42 is detached from the protector 26 and remains insidethe engagement member 41.

As the extension member 42 remains inside the engagement member 41, thespace surrounded by the plurality of engaging parts 46 is not pushed tospread outward in the radial direction as the plurality of engagingparts 46 are pressed outward in the radial direction. In addition, theabutment piece 29 abuts on the plurality of engaging parts 46 of theengagement member 41 when the protector 26 is pressed from one sidetoward the other side in the axial direction of the support part 37.Thus, the protector 26 after puncture is restricted from moving from oneside to the other side in the axial direction. Accordingly, it ispossible to inhibit the needle tip 21 a of the needle tube 21 afterpuncture from protruding again from the distal end face 26 a of theprotector 26. As a result, it is possible to maintain the needle tip 21a of the needle tube 21 after use in a safe state, and it is possible toinhibit the needle tip 21 a of the needle tube 21 after use frompuncturing against the intention of the user.

Further, since the needle tip 21 a of the needle tube 21 after use iscovered by the protector 26, it is possible to inhibit scattering ofblood adhering to the needle tip 21 a, and it is also possible toinhibit infection caused by the blood.

2. Second Embodiment

Next, a medicine injection apparatus according to a second embodimentwill be described with reference to FIGS. 5 to 7.

FIG. 5 is a cross-sectional view illustrating a state before puncture,FIG. 6 is a sectional view illustrating a state during puncture, andFIG. 7 is a sectional view illustrating a state after puncture.

The medicine injection apparatus according to the second embodiment isdifferent from the medicine injection apparatus 1 according to the firstembodiment in terms of configurations of a first member, a biasingmember, and a protector in an injection needle assembly. Thus, the firstmember, the biasing member, and the protector will be mainly describedhere. Common parts to those of the injection needle assembly 2 accordingto the first embodiment will be denoted by the same reference signs, andthe redundant description thereof will be omitted.

As illustrated in FIG. 5, an injection needle assembly 60 includes thehollow needle tube 21 and a needle hub 62 which holds the needle tube21. The needle hub 62 includes a first member 63, a second member 64into which the discharge part of the syringe 3 is fitted, the elasticmember 25, a protector 66, a biasing member 67, and a restrictionmechanism 68.

The first member 63 includes a base part 71, an adjustment part 72, astabilization part 73, a guide part 74, and a support part 77. The basepart 71 is formed in a substantially columnar shape. A housing recess 76is formed in the base part 71. The entire first end face in an axialdirection of the base part 71 is opened. The housing recess 76 is formedto be recessed in a substantially columnar shape from a first end to thesecond end in an axial direction of the base part 71. A support part 77is formed in the housing recess 76.

The support part 77 is provided at a central portion of a bottom surface76 a of the housing recess 76 and protrudes from the bottom surface 76 aof the housing recess 76 in the axial direction of the base part 71. Thesupport part 77 has a first pillar 77A and a second pillar 77B. Thefirst pillar 77A and the second pillar 77B are formed in a substantiallycolumnar shape.

The first pillar 77A protrudes in the axial direction of the base part71 from the bottom surface 76 a of the housing recess 76. The secondpillar 77B is provided at a central portion of a first end face 77 aA inan axial direction of the first pillar 77A and protrudes in the axialdirection of the base part 71. An axial center of the first pillar 77Aand an axial center of the second pillar 77B coincide with each other.An outer diameter of the second pillar 77B is set to be smaller than anouter diameter of the first pillar 77A.

In addition, the adjustment part 72 is provided on a first end face 77aB in an axial direction face of the second pillar 77B. The adjustmentpart 72 is provided at a central portion of the first end face 77 aB ofthe second pillar 77B. Further, an axial center of the adjustment part72 coincides with the axial centers of the first pillar 77A and thesecond pillar 77B.

Next, the protector 66 will be described. The protector 66 is formed ina tubular shape, and covers the second pillar 77B and the periphery ofthe adjustment part 72 through which the needle tube 21 passes and theneedle tip 21 a of the needle tube 21 in the state before puncturing theskin with the needle tube 21. The protector 66 is supported by aretaining member 83 and the support part 37 so as to be movable in theaxial direction.

The protector 66 is provided with an abutment piece 69 and a springabutment part 78. The abutment piece 69 is provided on an outerperipheral surface of the protector 66 on the second end side in theaxial direction. In addition, an inclined surface 69 a is formed on theabutment piece 69. The spring abutment part 78 is disposed at first endportion in the axial direction of the protector 66.

The spring abutment part 78 is an inner flange that is continuouslyprovided in the circumferential direction of an inner wall of theprotector 66 and protrudes inward in the radial direction of theprotector 66. An insertion hole 78 a through which the adjustment part72 and the needle tip 21 a of the needle tube 21 are inserted isprovided on the inner side in the radial direction of the springabutment part 78.

The biasing member 67 is disposed so as to cover the second pillar 77Bof the support part 77 and the periphery of the adjustment part 72 in acylindrical hole of the protector 66. First end portion in an axialdirection of the biasing member 67 abuts on the spring abutment part 78,and the second end portion in the axial direction of the biasing member67 abuts on the first end face 77 aA of the first pillar 77A. Further,the biasing member 67 biases the protector 66 toward one side in theaxial direction, that is, the needle tip 21 a side of the needle tube21.

Next, the restriction mechanism 68 will be described. The restrictionmechanism 68 has an engagement member 81 and an extension member 82,which is similar to the restriction mechanism 28 according to the firstembodiment.

The engagement member 81 has a cylindrical part 85 formed in asubstantially cylindrical shape and a plurality of engaging parts 86.The engagement member 81 is disposed in the housing recess 76. Theplurality of engaging parts 86 are provided with engagement pieces 86 a,respectively.

In addition, the extension member 82 is formed in a substantiallytubular shape, and is detachably attached to an outer peripheral portionof the protector 66 on the other side in the axial direction withrespect to the abutment piece 69. In addition, the extension member 42is provided with an extension part 88. An extension surface 88 a that isinclined with respect to the axial direction is formed in the extensionpart 88.

In addition, the first member 63 has the retaining member 83. Theretaining member 83 is formed in a substantially disc shape, and asupport hole 83 a is opened in a central portion thereof. The adjustmentpart 72, the second pillar 77B of the support part 77, and the protector66 are inserted through the support hole 83 a. Further, the retainingmember 83 supports the protector 66 so as to be movable along the axialdirection of the support part 77.

Next, an operation of the protector 66 of the injection needle assembly60 according to the second embodiment having the above-describedconfiguration will be described.

As illustrated in FIG. 5, the abutment piece 69 abuts on the retainingmember 83 in the state before puncture. At this time, the protector 66covers the second pillar 77B and the periphery of the adjustment part 72through which the needle tube 21 passes and the needle tip 21 a of theneedle tube 21. Accordingly, it is possible to inhibit erroneouspuncture of the needle tip 21 a of the needle tube 21 before puncturingthe skin with the needle tip 21 a side of the needle tube 21.

Next, when the distal end face 66 a of the protector 66 is pushed to theskin against the biasing force of the biasing member 67, the extensionmember 82 and the abutment piece 69 of the protector 66 are insertedinto the engagement member 81. Further, the protector 66 is supported bythe support hole 83 a of the retaining member 83, and the protector 66moves along the support part 77. Further, the needle protrusion surface72 a of the adjustment part 72 and the needle tip 21 a of the needletube 21 protrude from the insertion hole 78 a of the protector 66 asillustrated in FIG. 6.

At this time, the biasing member 67 is compressed by being elasticallydeformed between the spring abutment part 78 of the protector 66 and thefirst end face 77 aA of the first pillar 77A.

Next, when the injection needle assembly is separated from the distalend face 66 a of the protector 66, the biasing member 67 is releasedfrom pressing from the skin via the protector 66. Then, the protector 66is biased toward the needle tip 21 a side of the needle tube 21 by arestoring force (biasing force) of the biasing member 67.

As illustrated in FIG. 7, the abutment piece 69 pushes the plurality ofengaging parts 86 to spread outward in the radial direction, andfurther, passes a space among the plurality of engaging parts 86. Inaddition, the abutment piece 69 abuts on the retaining member 83. Then,the protector 66 covers the periphery of the needle tip 21 a of theneedle tube 21, and the needle tube 21 is housed in the protector 66. Atthis time, the extension member 82 remains inside the engagement member81.

Since the other configurations are the same as those of the injectionneedle assembly 2 according to the first embodiment, the descriptionthereof will be omitted. Even with the injection needle assembly 60configured as above, it is possible to obtain the same action and effectas those of the injection needle assembly 2 according to the firstembodiment described above.

In addition, the biasing member 67 is housed in the cylindrical hole ofthe protector 66 in the injection needle assembly 60 according to thesecond embodiment. Thus, the biasing member 67 is disposed closer to theneedle tip 21 a side of the needle tube 21 than the biasing member 27 ofthe injection needle assembly 2 according to the first embodiment.Accordingly, it is possible to set a length in an axial direction of thehousing recess 76, formed in the base part 71, to be shorter than thelength in the axial direction of the housing recess 36 according to thefirst embodiment, and it is possible to make the first member 63 smallerthan the first member 23 according to the first embodiment.

Further, it is possible to set a length in an axial direction of theengagement member 81, housed in the housing recess 76, to be shorterthan the length in the axial direction of the engagement member 41according to the first embodiment. As a result, it is possible to obtainthe reduction in size of the injection needle assembly 60.

Further, it is possible to cause the biasing member 67 to be separatedfrom the engagement member 81 and the extension member 82 of therestriction mechanism 68 when the biasing member 67 to be elasticallydeformed is housed in the cylindrical hole of the protector 66 anddisposed on a distal end side in the axial direction of the first member63. Accordingly, it is possible to inhibit the respective members frominterfering with each other when the biasing member 67 is elasticallydeformed, when extension member 82 moves, when the protector 66 moves,and when the plurality of engaging parts 86 of the engagement member 81are elastically deformed. As a result, it is possible to smoothlyperform the movement operation of the protector 66.

As above, the embodiments of the medicine injection apparatus and theinjection needle assembly according to the present invention have beendescribed including the action and effect thereof. However, the medicineinjection apparatus and the injection needle assembly according to thepresent invention are not limited to the above-described embodiments,and various modifications can be made within a scope not departing froma gist of the invention described in the claims.

Although the example in which the luer lock part is provided as the lockmechanism 12 has been described the above-described embodiments, thepresent invention is not limited thereto. A male screw part may beprovided in the discharge part to be screwed with a female screw partprovided in the cylindrical hole of the second member 24 of theinjection needle assembly 2.

REFERENCE NUMERAL LIST

-   -   1 . . . medicine injection apparatus,    -   2, 60 . . . injection needle assembly,    -   3 . . . syringe,    -   4 . . . pusher member,    -   21 . . . needle tube,    -   21 a . . . needle tip,    -   22, 62 . . . needle hub,    -   23, 63 . . . first member,    -   24, 64 . . . second member,    -   26, 66 . . . protector,    -   26 a, 66 a . . . distal end face,    -   27, 67 . . . biasing member,    -   28 . . . restriction mechanism,    -   29, 69 . . . abutment piece,    -   29 a, 69 a . . . inclined surface,    -   31, 71 . . . base part,    -   32, 72 . . . adjustment part,    -   32 a, 72 a . . . needle protrusion surface,    -   33, 73 . . . stabilization part,    -   33 a . . . end face,    -   34, 74 . . . guide part,    -   34 a . . . contact surface,    -   36, 76 . . . housing recess,    -   36 a, 76 a . . . bottom surface,    -   37 . . . support part,    -   40 . . . space,    -   41, 81 . . . engagement member,    -   42, 82 . . . extension member,    -   43, 83 . . . retaining member,    -   43 a, 83 a . . . support hole,    -   45, 85 . . . cylindrical part,    -   46, 86 . . . engaging part,    -   46 a, 86 a . . . engagement piece,    -   48, 88 . . . extension part,    -   48 a, 88 a . . . extension surface,    -   77A . . . first pillar,    -   77 aA, 77 aB . . . first end face,    -   77B . . . second pillar,    -   78 . . . spring abutment part,    -   78 a . . . insertion hole

What is claimed is:
 1. An injection needle assembly comprising: a needletube having a needle tip configured to puncture a living body; a needlehub holding the needle tube; a protector movable between a firstposition at which the needle tip of the needle tube is covered and asecond position at which the needle tip of the needle tube is exposed,the protector comprising an abutment piece; a biasing member configuredto bias the protector toward the needle tip of the needle tube along anaxial direction of the needle tube; a retaining member that supports theprotector such that the protector is movable along the axial directionof the needle tube, wherein the abutment piece abuts on the retainingmember when the protector is moved to the first position; and arestriction mechanism configured such that, after the protector hasmoved from the first position to the second position and has furtherreturned from the second position to the first position, the restrictionmechanism restricts the protector from moving from the first position tothe second position again, wherein the restriction mechanism comprises:an engagement member having an engaging part that is elasticallydeformable in a radially outward direction of the needle tube, and anextension member that is detachably attached to the protector, theextension member comprising an extension part that pushes an openingformed by the engaging part to spread in the radially outward directionwhen the protector moves from the first position to the second position,wherein the extension member passes through the engaging part and isinserted into the engagement member together with the abutment piecewhen the protector moves from the first position to the second position,and wherein the extension member is detached from the protector andengaged with the engaging part when the protector returns to the firstposition from the second position.
 2. The injection needle assemblyaccording to claim 1, wherein: the needle hub is formed with a housingrecess that is open on a needle tip side of the needle tube, and therestriction mechanism is housed in the housing recess.
 3. The injectionneedle assembly according to claim 1, wherein: the biasing member is ona needle tip side of the restriction mechanism in the axial direction ofthe needle tube.
 4. The injection needle assembly according to claim 1,further comprising: an adjustment part that is provided around theneedle tube, is configured to come into contact with skin when theneedle tube punctures the living body, and has a needle protrusionsurface from which the needle tip of the needle tube protrudes, whereinthe protector covers a periphery of the adjustment part when theprotector is at the first position.
 5. The injection needle assemblyaccording to claim 4, further comprising: a stabilization part thatextends from the needle hub, is disposed so as to cover the needle tubeand a periphery of the protector, and has an end face configured to comeinto contact with the skin when the needle tube punctures the livingbody; and a guide part that is formed in a flange shape protruding in aradial direction from a periphery of the stabilization part so as to besubstantially perpendicular to an outer side of the stabilization partin a radial direction.
 6. A medicine injection apparatus comprising: aninjection needle assembly comprising a needle tube having a needle tipconfigured to puncture a living body; and a syringe that is detachablyattached to the injection needle assembly, wherein the injection needleassembly comprises: a needle hub holding the needle tube, a protectormovable between a first position at which the needle tip of the needletube is covered and a second position at which the needle tip of theneedle tube is exposed, the protector comprising an abutment piece, abiasing member configured to bias the protector toward the needle tip ofthe needle tube along an axial direction of the needle tube, a retainingmember that supports the protector such that the protector is movablealong the axial direction of the needle tube, wherein the abutment pieceabuts on the retaining member when the protector is moved to the firstposition, and a restriction mechanism configured such that, after theprotector has moved from the first position to the second position andhas further returned from the second position to the first position, therestriction mechanism restricts the protector from moving from the firstposition to the second position again wherein the restriction mechanismcomprises: an engagement member having an engaging part that iselastically deformable in a radially outward direction of the needletube, and an extension member that is detachably attached to theprotector, the extension member comprising an extension part that pushesan opening formed by the engaging part to spread in the radially outwarddirection when the protector moves from the first position to the secondposition, wherein the extension member passes through the engaging partand is inserted into the engagement member together with the abutmentpiece when the protector moves from the first position to the secondposition, and wherein the extension member is detached from theprotector and engaged with the engaging part when the protector returnsto the first position from the second position.